Comparison of four design environments employed to analyze a switched-capacitor DC-DC converter

Abstract

This paper compares the performance of four popular design environments for analog and mixed-signal applications - Virtuoso from Cadence Inc., SIMetrix/SIMPLIS, Simulink and CppSim - when used for system level analysis of a standard switched capacitor DC-DC converter. Virtuoso is the most expensive of the four but it has the best user interface and its Spice-level circuit simulators provide very good accuracy. Also, it allows complete top-down design, from system- to circuit-level within the same environment. However, it may not be best suited for first-pass system-level analysis of switching circuits such as DC-DC converters due to its long simulation time and convergence issues. Numerical solvers such as MATLAB - Simulink and CppSim represent functional blocks by input-state-output relationships, thus avoiding the solving of large sets of simultaneous equations. This reduces dramatically the simulation time at the expense of poorer accuracy. SIMetrix/SIMPLIS converts non-linear models to a piecewise linear straight-line model achieving a fast simulation time for switching circuits. For a fair comparison, the same circuit was analyzed under the same conditions by using the four design environments; the trade-offs between cost, accuracy and simulation time are highlighted.